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• Pause time and other pause frame control bits †
• Receive and Transmit Flow control bits †
• Flow Control Busy/Backpressure Activate †
7. Program the Interrupt Mask register bits, as required, and if applicable, for your configuration. †
8. Program the appropriate fields in Register 0 (MAC Configuration Register). For example, Interframe
gap while transmission and jabber disable. Based on the Auto-negotiation you can set the Duplex mode
(bit 11) or port select (bit 15). †
9. Set Bit 3 (TE) and Bit 2 (RE) in Register 0 (MAC Configuration Register). †
Do not change the configuration (such as duplex mode, speed, port, or loopback) when the EMAC
DMA is actively transmitting or receiving. The Software should change these parameters only when
the EMAC DMA transmitter and receiver are not active.
Note:
Performing Normal Receive and Transmit Operation
For normal operation, perform the following steps: †
1. For normal transmit and receive interrupts, read the interrupt status. Then, poll the descriptors, reading
the status of the descriptor owned by the Host (either transmit or receive). †
2. Set appropriate values for the descriptors, ensuring that transmit and receive descriptors are owned by
the DMA to resume the transmission and reception of data. †
3. If the descriptors are not owned by the DMA (or no descriptor is available), the DMA goes into SUSPEND
state. The transmission or reception can be resumed by freeing the descriptors and issuing a poll demand
by writing 0 into the TX/RX poll demand register (Register 1 (Transmit Poll Demand Register) and
Register 2 (Receive Poll Demand Register). †
4. The values of the current host transmitter or receiver descriptor address pointer can be read for the debug
process (Register 18 (Current Host Transmit Descriptor Register) and Register 19 (Current Host Receive
Descriptor Register). †
5. The values of the current host transmit buffer address pointer and receive buffer address pointer can be
read for the debug process (Register 20 (Current Host Transmit Buffer Address Register) and Register
21 (Current Host Receive Buffer Address Register). †
Stopping and Starting Transmission
Perform the following steps to pause the transmission for some time: †
Ethernet Media Access Controller
Altera Corporation
cv_54017
Performing Normal Receive and Transmit Operation
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2013.12.30